Measurement of the radiative energy output of flash lamps by means of thermal thin probes

Flash lamps are widely used excitation sources in the field of non-destructive testing with active thermography. Though the realized energy density in front of the investigated object is a significant factor with regard to detection sensitivity, only few data concerning this issue have been published so far. It is shown here that local energy densities can be estimated by means of a simple metal plate, which exhibits a certain temperature increase after flash excitation. After discussing the underlying calorimetric principle the sensor concept is reviewed using constant blackbody radiation and short laser pulses, since both kinds of sources generate known energy densities. The relative uncertainty of measurements of the energy density is found to be in the range of 10%. The last part of the present paper describes an application for characterizing the radiation of a usual 6 kJ flash lamp. The energy conversion efficiency was found to be only about 11%.